/[ascend]/trunk/models/johnpye/grena/sunpos_grena.h
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Revision 2470 - (hide annotations) (download) (as text)
Sat May 28 09:12:38 2011 UTC (11 years, 2 months ago) by jpye
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Working on conversion of Grena code to C.
1 jpye 2470 /* ASCEND modelling environment
2     Copyright (C) 2011 Carnegie Mellon University
3 jpye 2469
4 jpye 2470 This program is free software; you can redistribute it and/or modify
5     it under the terms of the GNU General Public License as published by
6     the Free Software Foundation; either version 2, or (at your option)
7     any later version.
8    
9     This program is distributed in the hope that it will be useful,
10     but WITHOUT ANY WARRANTY; without even the implied warranty of
11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12     GNU General Public License for more details.
13    
14     You should have received a copy of the GNU General Public License
15     along with this program; if not, write to the Free Software
16     Foundation, Inc., 59 Temple Place - Suite 330,
17     Boston, MA 02111-1307, USA.
18     */
19    
20 jpye 2469 /* WARNING: this is a FIRST DRAFT of the code and HAS NOT BEEN CHECKED yet. */
21    
22     /** @FILE
23     Code reproduced with minor cosmetic changes from:
24     R Grena (2008), An algorithm for the computation of the solar position,
25     Solar Energy (82), pp 462-470.
26    
27     This header file contains the declaration of a class which includes all the
28     input and output data, and the function that performs the calculation.
29    
30     To calculate the sun position, follow these steps:
31    
32     1. include this file.
33     2. declare a variable of type SunCoord.
34     3. Initialise the variable given the 9 input quantities required.
35     This can be done in the declaration, listing the quantities between
36     commas, or calling the function SetCoord(). In both cases, only the first
37     four quantities are required; the others default to standard values
38     (pressure = 1 atm, T = 20 ��C, 0 for all the other quantities) if omitted.
39     Longitude and latitude must be given in RADIANS, pressure in ATM,
40     temperature in ��C.
41     Day, Month and Year are integer, UT in decimal hour from 0 to 24 (e.g.
42     3:30 pm becomes 15.5).
43     4. Call the Calculate() method of the SunCoord object.
44    
45     Example:
46     (see the original publication)
47    
48     Warning: in order to improve accessibility and efficiency, there is not
49     access control in the class. The user is free to directly access and
50     modify all the data and there is not any control of consistency. Some
51     caution in the use of the class is advisable.
52     */
53     #ifndef SUNPOS_GRENA_H
54     #define SUNPOS_GRENA_H
55    
56     #include <iostream>
57     #include <cmath>
58    
59     #ifndef PI
60     # define PI 3.14159265358979
61     #endif
62    
63 jpye 2470 /**
64     Structure to hold sun position data, both input data as well as calculated
65     output data.
66 jpye 2469
67 jpye 2470 FIXME convert fields p, T to base SI units Pa and K.
68     */
69     typedef struct SunPos_struct{
70 jpye 2469 // input data
71 jpye 2470 double t; ///< Ephemeris Julian Day, offset such that 0 = noon 1 Jan 2003.
72     double latitude; ///< Latitude (N = positive??), in RADIANS.
73     double longitude; ///< Longitude (E = positive??), in RADIANS.
74     double p; ///< Pressure, in ATM (used for refraction calculation)
75     double T; ///< Temperature, in ��C (used for refraction calculation)
76     } SunPos;
77 jpye 2469
78 jpye 2470 // functions
79 jpye 2469
80 jpye 2470 /** Calculate time given the input date fields and store it in the SunPos object.
81     @param UT fractional universal time (GMT) in hours from midnight (or fractional hours as required)
82     @param Day Day of the month, starting at 1??
83     @param Month Month of the year, starting at 1??
84     @param Year Year, eg 2011.
85     @param Delta_t Difference between UT and Terrestrial Time, in seconds.
86     */
87     void SunPos_calc_time(SunPos *S, double UT, int Day, int Month, int Year, double Delta_t);
88 jpye 2469
89 jpye 2470 /** Set time directly in days since noon 1 Jan 2003 UTC. */
90     void SunPos_set_time(SunPos *S, double t);
91 jpye 2469
92 jpye 2470 /** Set location of observer on Earth
93     @param latitude latitude in RADIANS!
94     @param longitude longitude in RADIANS!
95     */
96     void SunPos_set_lat_long(SunPos *S, double latitude, double longitude);
97 jpye 2469
98 jpye 2470 /** Set local atmospheric conditions
99     @param p Pressure in ATM
100     @param T Temperature in ��C
101     */
102     void SunPos_set_pressure_temp(SunPos *S, double p, double T)
103 jpye 2469
104 jpye 2470 /**
105     Calculate the sun position in local spherical coordinates.
106     @param S sun position input data object (set using above functions)
107     @param zenith zenith angle in radians (output)
108     @param azimuth azimuth angle in radians (output)
109     */
110     void SunPos_calc_zen_azi(SunPos *S, double *zenith, double *azimuth);
111 jpye 2469

john.pye@anu.edu.au
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